ANTWERP, Belgium – Martin Audio's new Multi-Cellular Loudspeaker Array (MLA) system appears to be holding some promise for Belgian festival promoters and production companies who are concerned with proposed 100dB LAeq (15) and 116dB (C) maximum limits in public areas.
Joke Schauvliege, the Flemish minister for Environment, Nature and Culture (CD&V) recently pushed to clarify noise limits proposed for Belgian pop festival sound thresholds.
Karel de Piere and his team from technology specialists, FACE, had already tested Martin Audio's MLA nine months earlier, during an Amnesty International concert in Antwerp's Groenplaats. They followed that with a demo at the Antwerp Sportpaleis arena, and were confident the MLA system would address the noise limit concerns.
The MLA system was designed to minimize the variations in frequency response and sound pressure levels – effective over distances of up to 150 meters – using predictive analysis instead of trial-and-error. With MLA's multi-cellular approach, each cell is individually addressed by its own DSP and Class D amplifiers.
"This means that wherever they are sat in the festival field, each person will receive the same sound image at the same volume," noted de Piere, alluding to data-backed studies that challenge conventional notions about what is possible in a live-sound environment.
"If a concert organizer wanted to achieve 100dB at the back of the site by the conventional method, he would need to have 110dB in front-by the speaker system. But we wanted to prove that this is now no longer the case. With MLA, the volume can be at exactly the same level throughout the coverage area, while we can limit the sound immediately beyond that-for the neighbors or the festival campsite.
"The system also ensures that there is virtually no sound return to the stage-so it is nicer for the musicians to play through the MLA."
De Piere recalled that, when the local environmental police arrived onsite at the Groenplaats, they didn't believe that the 102dB registering at the mix position would not spill out to the neighboring businesses and residents surrounding the square. "But what we saw was an alarming tapering off of 12dB [beyond the sound field] over the final 15 meters-to hit 90dB. People were telling me it was not possible."
The recent evaluation at the FACE HQ in Boom saw Martyn "Ferrit" Rowe, Martin Audio's technical training manager, demonstrate the theory to close to 90 festival organizers, sound technicians and members of the press in a seminar presentation-backed up by practical examples from the U.S. tour for The Zac Brown Band.
Rowe and FACE also provided an MLA system demonstration in an adjacent park-which happens to be the same location for the dance festival, Tomorrowland. The site measures 80 meters wide by 160 meters deep. Two PA wings were set at a distance of 24 meters, with 12-box hangs per side trimmed at a 10 meter height. Another 12 MLX subs were stacked adjacent to each other, forming a single broadside array along the front.
To give the festival site further authenticity, a mix tent (which also contained drinks and heating) was positioned 70 meters from the MLA. The system played a variety of music from a CD source.
Assisted by Peter van der Geer from Event Acoustics Projects, onscreen readings were taken at 20m, 60m, 80m and the final one at 130m-with one overview screen placed at the mixing position.
"We could clearly see the four levels," said FACE's Steven Kemland. "At the first three measurement positions, the level was the same, but the drop off was -15dB at the 130 meter mark – which was quite impressive. The environmental people from Antwerp [who had sanctioned the event on the Groenplaats] also used their own measurement instruments as proof of concept."
Knowing that all feedback had to be supplied to Minister Schauvliege by Feb. 11, FACE noted that the exercise probably played a key role. "It was necessary that our guests could experience the technical solution for themselves- proving that the system would deliver an identical SPL to everyone throughout the site, with a steep ‘tapering off' outside the festival zone.
"After the demonstration, those present were still marveling at how the system could throw consistently over that distance and then suddenly fall off," Kemland continued. "I think as a result everyone will know that there is a future beyond line array. The event was a complete success."
"This was a perfect situation to prove to festival organizers, sound technicians, politicians and press the validity of this system," said de Piere. "We believe we have gone a long way towards establishing MLA on festival riders should this 100dB sound threshold become law."
For more information, please visit www.martin-audio.com.
